1. Field of the Invention
The present invention relates to photoconductors for electrophotography, and particularly to a photoconductor for electrophotography which is made of an organic photoconductive material, and has excellent stability of characteristics in continuous repeated use.
2. Description of the Prior Art
Photoconductors for electrophotography (hereinafter to be referred to as a photoconductor) which have heretofore been used in a wide area is inorganic photoconductors in which use is made of inorganic photoconductive substances such as selenium, selenium alloys, zinc oxide and cadmium sulfide. On the other hand organic photoconductors in which use is made of organic photoconductive substances have been developed and been put into practical use by virtue of the advantageous features such as flexibility, thermal stability, and/or a film forming capacity. They include a photoconductor comprising poly-N-vinylcarbazole and 2,4,7-trinitrofluoren-9-on (disclosed in U. S. Pat. No. 3,484,237), a photoconductor using an organic pigment as a main component (disclosed in Japanese Patent Application Laying-Open No. 47-37,543), a photoconductor using as a main component a eutectic complex composed of a dye and a resin (disclosed in Japanese Patent Application Laying-Open No. 47-10,785). Although organic materials which have a number of advantageous features mentioned above, however they have not been used in a wide area by virtue of the features which are less advantageous than inorganic materials in photosensitivity, stability of characteristics in continuous repeated use and durability. In recent years, organic photoconductor having excellent property of being charged and photosensitivity have been developed and spread rapidly.
It is required that photoconductors usually have stability of conductive characteristic in continuous repeated use at an image formation process in the electrophotographic method. However, the fact is that there have been obtained no organic photoconductors fully satisfying the stability of characteristic required on the market at the present. As organic photoconductors are used repeatedly, there are problems that they are getting to be unsuitable for use by virtue of the disadvantageous features such as decreasing the electric potential, increasing the residual electric potential, changing in the photosensitivity and debasing the quality of the image formed.